1. Field of the Invention
The invention relates to a storage battery, more particularly to a storage battery which has a battery housing with a cover device that offers added protection against leakage.
2. Description of the Related Art
A conventional storage battery comprises a battery housing which includes a casing for receiving cell plates and electrolyte therein, and a cover device for closing an open top end of the casing. In use, the heat that is generated during electrolysis causes the electrolyte to evaporate. The vaporized electrolyte is then released to the atmosphere via a vent hole in the cover device. Thus, there is a need to replenish the electrolyte in the battery housing periodically.
To overcome the above drawback, a battery housing with a cover device that is capable of recovering the vaporized electrolyte has been developed, thereby obviating the need for replenishing the electrolyte in the battery housing periodically. Referring to FIG. 1, the battery housing 1 comprises a rectangular casing 11 and a cover device 2 heat-sealed to an open top end of the casing 11. The cover device 2 includes a main cover part 21 and a sub-cover part 22. The main cover part 21 has a plate body 210 with a top face that is formed with a rectangular confining wall 211. The confining wall 211 is divided by a plurality of spaced transverse dividers 212 and a longitudinal divider 213 into a plurality of first and second chambers 2110, 2111. Each of the first chambers 2110 has a bottom formed with a fluid inlet 214 for pouring electrolyte into a respective cell compartment 111 of the casing 11. Each of a plurality of annular lips 218 projects upwardly from the plate body 210 and is disposed around a respective one of the fluid inlets 214. Each of the second chambers 2111 has a bottom which is formed with an upwardly projecting partition unit that confines a condensate groove 215 and which is further formed with a return hole 216 and a vent hole 217.
The sub-cover part 22 is secured integrally to the main cover part 21 after electrolyte has been poured into the cell compartments 111 via the fluid inlets 214. The sub-cover part 22 is heat-sealed to the main cover part 21 at top edges of the confining wall 211, the dividers 212, 213, and the partition units. The sub-cover part 22 thus seals a top end of the condensate grooves 215. The sub-cover part 22 further has a bottom face formed with a plurality of annular projections 221 which are heat-sealed to the annular lips 218, thereby closing the fluid inlets 214.
Referring to FIG. 2, the condensate groove 215 in each of the second chambers 2111 is communicated fluidly with a respective one of the cell compartments 111 via the return hole 216 and the vent hole 217. When a storage battery which employs the battery housing 1 is in use, the electrolyte in the cell compartments 111 undergo electrolysis and evaporate due to the heat that is generated. The vaporized electrolyte flow into the condensate grooves 215 via the return holes 216 or the vent holes 217 and contact the bottom face of the subcover part 22. Since the sub-cover part 22 is exposed to the atmosphere, the temperature of the sub-cover part 22 is less than that of the vaporized electrolyte entering the condensate grooves 215. Thus, heat transfer occurs so that the vaporized electrolyte condenses, and the resulting condensate flows back into the corresponding cell compartment 111 via the return holes 216. Therefore, since the vaporized electrolyte is not released to the atmosphere and is instead recovered, there is no need to replenish the electrolyte in the battery housing 1 periodically.
It is noted that sealing of the sub-cover part 22 to the main cover part 21 has to be conducted with a high degree of precision in order to guard effectively against leakage. Otherwise, when transporting the storage battery, the electrolyte in the cell compartments 111 can flow easily into the condensate grooves 215 and leak out of the cover device 2 via crevices between the main cover part 21 and the subcover part 22 if the storage battery is in an abnormal position, e.g. toppled forward, backward or sideways.